1. Field of the Invention
The present invention relates to a dust collecting apparatus for purifying high-temperature gases.
2. Description of the Prior Art
In the case that high-temperature gases are utilized as a source of thermal energy, it is required to eliminate dust from the high-temperature gases for use in a clean condition. In the case that exhaust gases are discharged into the atmospheric air, it is also required to eliminate dust from the exhaust gases.
To satisfy the requirements described above, there have been various dust collecting apparatuses for purifying the high-temperature gases. In Japanese Patent Laid-open Publication No. 4-354506, there is disclosed a dust collecting apparatus of this kind which has an upright cylindrical housing provided therein with a pair of radially spaced vertical partition wall members secured at their side edges to an internal peripheral wall of the cylindrical housing to form a pair of vertical gas induction passages along the internal peripheral wall and to form a discharge passage at the center of the cylindrical housing, plural pairs of vertically spaced horizontal support members fixed to the vertical parition wall members, plural sets of filter assemblies vertically mounted on each pair of the horizontal support members in such a manner that the filter assemblies are exposed at their inner ends to the vertical discharge passage and at their outer ends to the vertical induction passages, the filter assemblies each being composed of a plurality of filter elements integrally assembled as a unit, each of the filter elements being made of porous ceramic material and having a thin walled cellular structure formed with a plurality of axial passages separated from each other by thin partition walls, wherein a first group of the axial passages are opened at their one ends to introduce therein high-temperature gases to be purified from the vertical induction passage and closed at their other ends, while a second group of the axial passages are closed at their one ends and opened at their other ends to discharge purified gases therefrom into the vertical discharge passage.
Although the purifying efficiency of the dust collecting apparatus is extremely high, the component parts of the dust collecting apparatus such as the cylindrical housing body, the vertical partition wall members, the horizontal support members and the filter assemblies are made of different materials, That is to say, the vertical partition wall members are, in general, made of metal, while the filter assemblies are made of porous ceramic material superior in durability. It has been, however, found that when the dust collecting apparatus is adapted to purify high-temperature gases at a high temperature more than 700.degree. C., the joint portions of the filter assemblies with the vertical partition wall members are applied with heavy stress due to difference in thermal expansion and contraction of the component parts, resulting in damage of the filter assemblies in a short period of time.